Measuring Surface and Interfacial Tension In Situ in Microdripping Mode for Electrohydrodynamic Applications.

Karim I Budhwani,Mohamed M Selim,Gerald M Pekmezi

doi:10.3390/mi11070687

Karim I Budhwani, Mohamed M Selim + Show 1 more

Open Access

https://doi.org/10.3390/mi11070687

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Abstract

Walking on water is made possible, at least for tiny insects, by molecular interaction at the interfaces of dissimilar materials. Impact of these interactions—surface tension (SFT) and, more broadly, interfacial tension (IFT)—is particularly evident at micro and nano sizescales. Thus, implications of walking on water can be significant for SFT or IFT (S/IFT)-driven nanofabrication technologies, such as electrohydrodynamic atomization (EHDA), in developing next generation biomimetic microphysiological systems (MPS) and drug delivery systems (DDS). However, current methods for estimating S/IFT, based on sessile drops or new surface formation on a ring or plate, are unsuitable for integration with EHDA assemblies used in electrospinning and electrospraying. Here, we show an in situ method for estimating S/IFT specifically devised for EHDA applications using signal processing algorithms that correlate the frequency and periodicity of liquid dispensed in EHDA microdripping mode with numerical solutions from computational fluid dynamics (CFD). Estimated S/IFT was generally in agreement with published ranges for water–air, 70% ethanol–air, chloroform–air, and chloroform–water. SFT for solutions with surfactants decreased with increasing concentrations of surfactant, but at relatively higher than published values. This was anticipated, considering that established methods measure SFT at boundaries with asymmetrically high concentrations of surfactants which lower SFT.

Highlights

With one in two men and one in three women poised to be diagnosed with cancer [1], disease modeling with biomimetic microphysiological systems (MPS) and targeted drug delivery systems (DDS) is of keen interest in micro and nanoscale processing
Mechanisms to improve the throughput of nanofibrous scaffolds continue to gain momentum [3]
The flatline was resolved by replacing it with two points at 72.5 ± 0.3 dyne/cm with simple frequency averages for either side

Summary

Introduction

With one in two men and one in three women poised to be diagnosed with cancer [1], disease modeling with biomimetic microphysiological systems (MPS) and targeted drug delivery systems (DDS) is of keen interest in micro and nanoscale processing. EHDA fabrication technologies, such as electrospinning (ESp) and electrospraying (ESy), offer promising pathways in both MPS and DDS applications. Nanofibrous porous scaffolds produced using ESp would be more suitable for recapitulating the in vivo tissue microenvironment in MPS, for modeling organ–capillary transport, the air–liquid interface, and tumor progression [2]. New multiplexing and planar arrays [14], and mechanisms for optimizing these [15], continue to emerge to meet the increasing throughput demands of such applications. Other limiting factors, such as clean room fabrication, are being overcome with additive manufacturing capabilities [16]

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